Following the common setting in 3D point cloud detection, the point clouds are divided into equally spaced voxels. For the point cloud with range \(W\times H\times D\)  along the \(X\times Y\times Z\)  respectively, the size of a voxel is \(v_W\times v_H\times v_D\)  accordingly. The total number of voxels that contains point clouds is \(n_v\) . Following the 3D object detector benchmark SECOND [1]}, we directly calculate the mean of point features with the 3D coordinates and reflectance intensities in a certain voxel as the voxel-wise representation.
